Variable turbocharger and control method for the same

ABSTRACT

A variable turbocharger including a turbine housing, a first scroll fluidly communicating with a turbine, a second scroll formed along an outside of the first scroll, wherein the first scroll and the second scroll are disposed within the turbine housing for exhaust gas to exhaust through the turbine, a partitioning unit for selectively separating the first scroll and the second scroll, and a flux control valve disposed at the exhaust gas inflow portion and selectively coupled to the partitioning unit for blocking the exhaust gas from flowing into the second scroll. The variable turbocharger may prevent turbo lag at a low speed and be highly efficient at a high speed.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to and the benefit of KoreanPatent Application No. 10-2008-0010787, filed on Feb. 1, 2008, theentire contents of which are incorporated herein for all purposes bythis reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a variable turbocharger and a controlmethod for the same. More particularly, the present invention relates toa variable turbocharger and a control method for the same that mayprevent turbo lag at a low speed and be highly efficient at a highspeed.

2. Description of Related Art

In a conventional internal combustion engine, negative pressuregenerated during an intake stroke induces a mixture of air into acylinder. This is called natural aspiration or normal aspiration.However, a valve opened time is too short to sufficiently intake the airmixture, so forcible pumping is used for enhancing the volume effect ofa cylinder, effective pressure ratio, and explosion pressure, therebyimproving output. This is called turbocharging, and an apparatus forturbocharging is called a turbocharger.

A conventional turbocharger 105, as shown in FIG. 1, includes a turbine101 and a compressor 103, and is connected with an exhaust manifold 109of an engine 107 for receiving exhaust gas.

The compressor 103 intakes air from an air cleaner 111 via an intakepipe 119, and the air is cooled in an intercooler 113 and supplied tothe engine 107 via an intake manifold 115.

The turbine 101 is connected with an exhaust pipe 117 exhausting theexhaust gas.

Thus, rotation of the turbine 101 induced by the exhaust gas of theengine 107 turns the compressor 103 connected with the turbine 101 by ashaft 121 and the cooled and compressed air is supplied from the aircleaner 111 to the intake manifold 115.

FIG. 2 shows a partial cross-section of a conventional turbocharger, andshows a turbine housing 123 provided with an inlet 122 into which theexhaust gas flows.

The turbine 101 that is connected with the compressor 103 by a shaft 121is disposed within the turbine housing 123.

The characteristics of the turbine 101 are determined by an A/R ratio,wherein A indicates a cross-section of the inlet 122, R indicates adistance between the center of the turbine 101 and the center of thecross-section of the inlet 122, and the A/R ratio means a value of Adivided by R. If the A/R ratio is small, the turbine 101 is sensitive toacceleration and resisting force to exhaust tends to be increased at ahigh speed.

A conventional A/R ratio is 0.5-1.0. The lower the A/R ratio, the fasterthe turbocharging is at low RPM, but performance is deteriorated at highRPM.

That is, when the A/R ratio is high, turbo lag may be occurred at lowRPM, however output is improved at high RPM.

The information disclosed in this Background of the Invention section isonly for enhancement of understanding of the general background of theinvention and should not be taken as an acknowledgement or any form ofsuggestion that this information forms the prior art already known to aperson skilled in the art.

BRIEF SUMMARY OF THE INVENTION

Various aspects of the present invention have been made in an effort toprovide a variable turbocharger and a control method for the same thatmay prevent turbo lag at low speed and may be highly efficient at highspeed.

A variable turbocharger according to various aspects of the presentinvention may include a turbine housing, a first scroll fluidlycommunicating with a turbine, a second scroll formed along an outside ofthe first scroll, wherein the first scroll and the second scroll aredisposed within the turbine housing for exhaust gas to exhaust throughthe turbine, a partitioning unit for selectively separating the firstscroll and the second scroll, and a flux control valve disposed at theexhaust gas inflow portion and selectively coupled to the partitioningunit for blocking the exhaust gas from flowing into the second scroll.

In various embodiments, the partitioning unit includes a scrollpartition that selectively separates the turbine housing between thefirst scroll and the second scroll, and a partition controlling unit fordriving the scroll partition. The partition controlling unit may includea guide unit configured to guide the scroll partition, and a controllinglink connected with the scroll partition and configured to move thescroll partition along the guide unit. The controlling link may includea first lever pivotally coupled to the scroll partition, a second leverconnected with the first lever, and a third lever connected with thesecond lever. The scroll partition may be configured to move based on anoperation of the third lever.

In various embodiments, the partition controlling unit includes aninclined unit disposed under the scroll partition, and a drive levermoving along the inclined unit thereby causing the scroll partition tomove. The scroll partition may include an elastic portion for supplyingrestoring force. The partition controlling unit may include a rackconnected to the scroll partition, and a drive gear engaged with therack, wherein the drive gear drives the rack. The scroll partition maybe disposed such that cross-sections of the first scroll and the secondscroll decrease along an inflow direction of the exhaust gas. Thepartitioning unit may include a scroll partition that selectivelyseparates the turbine housing with the first scroll and the secondscroll, and a partition controlling unit for driving the scrollpartition.

Various aspects of the present invention are directed to a controlmethod for a variable turbocharger including a control method for avariable turbocharger including detecting vehicle information,determining an exhaust gas inflow mode based on the vehicle information,opening/closing a flux control valve, and opening/closing a scrollpartition.

The detecting of the vehicle information may include detecting at leastone of vehicle speed, throttle opening, acceleration, and acceleratorpedal angle. The exhaust gas inflow mode may include a first mode inwhich exhaust gas flows through a first scroll, and a second mode inwhich exhaust gas flows through the first scroll and a second scroll.The opening/closing of the flux control valve may selectively blocksexhaust gas from flowing into the second scroll. The opening/closing ofthe scroll partition may selectively separates the first scroll and thesecond scroll. The opening/closing of the scroll partition and theopening/closing of the flux control valve may be simultaneouslyexecuted.

The opening/closing of the scroll partition may be executed with apartition controlling unit for opening/closing the scroll partition. Thepartition controlling unit may include a first lever pivotally coupledto the scroll partition, a second lever connected to the at least afirst lever, and a third lever connected to the second lever,

wherein the scroll partition is opened/closed by rotation of the thirdlever. The opening/closing of the scroll partition may be executed witha partition controlling unit for opening/closing the scroll partition.The partition controlling unit may include at least a first leverpivotally coupled to the scroll partition, a second lever pivotallyconnected with the at least a first lever, and a third lever pivotallyconnected with the second lever, wherein the scroll partition isopened/closed by rotation of the third lever. The opening/closing scrollpartition may be executed with a partition controlling unit foropening/closing the scroll partition. The partition controlling unit mayinclude a rack disposed under the scroll partition, and a drive gearengaged with the rack, wherein the scroll partition is opened/closed byrotation of the drive gear.

As described above, a variable turbocharger and a control method for avariable turbocharger according to various aspects of the presentinvention that may prevent turbo lag at low speed and may be highlyefficient at high speed with a sufficient cross-section of an inlet forexhaust gas is provided.

The variable turbocharger and the control method for a variableturbocharger according to exemplary embodiments of the present inventionmay prevent exhaust gas leaks and resistance at low speed and mayprevent wasting energy at high speed without obstacles in a scroll.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description of the Invention, which togetherserve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a conventional turbocharger.

FIG. 2 is a partial cross-section of the conventional turbocharger ofFIG. 1.

FIG. 3 shows operations of an exemplary variable turbocharger accordingto an aspect of the present invention at low speed and high speed.

FIG. 4 shows partial cross-sections of the exemplary variableturbocharger according various aspects of the present invention forexplaining operations at low speed and high speed.

FIG. 5 is a partial exploded view of the exemplary variable turbochargeraccording to various aspects of the present invention.

FIG. 6 shows a partition controlling unit of the exemplary variableturbocharger according to various aspects of the present invention.

FIG. 7 shows a partition controlling unit of an exemplary variableturbocharger similar to that of FIG. 4.

FIG. 8 shows a partition controlling unit of an exemplary variableturbocharger similar to that of FIG. 4.

FIG. 9 shows a partition controlling unit of an exemplary variableturbocharger similar to that of FIG. 4.

FIG. 10 is a block diagram of a control method for a variableturbocharger according to various aspects of the present invention asshown in FIG. 3.

FIG. 11 is a flow chart for explaining the control method for anexemplary variable turbocharger according to various aspects of thepresent invention as shown in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

FIG. 3 shows operations of a variable turbocharger according to anexemplary embodiment of the present invention at low speed and highspeed, and FIG. 4 shows partial cross-sections of the variableturbocharger according to the exemplary embodiment of the presentinvention explaining operations at low speed and high speed.

FIG. 5 is a partial exploded view of the variable turbocharger accordingto the present invention, and FIG. 6 shows a partition controlling unitof the variable turbocharger.

A variable turbocharger according to an exemplary embodiment of thepresent invention, as shown in FIG. 3 to FIG. 6, includes a turbinehousing 310, a first scroll 314, and a second scroll 316 formed aroundthe first scroll 314, and the first scroll 314 and the second scroll 316are disposed within the turbine housing 310 for exhaust gas to exhaustvia a turbine 312.

The variable turbocharger also includes a partitioning unit 330 forselectively separating the first scroll 314 and the second scroll 316,and a flux control valve 320 disposed to an exhaust gas inflow portion311 for selectively blocking the exhaust gas to flow into the secondscroll 316.

The partitioning unit 330 includes a scroll partition 332 that isselectively inserted between the first scroll 314 and the second scroll316, and a partition controlling unit 340 for driving the scrollpartition 332. By “selectively inserted”, it is meant that the scrollpartition is disposed between the first scroll and second scroll suchthat it can direct all or a portion of a flow into the first scroll orsecond scroll.

The partition controlling unit 340 includes a guide unit 342 for guidingthe scroll partition 332 and a controlling link 344 connected with thescroll partition 332 for the scroll partition 332 to move along theguide unit 342.

The controlling link 344 includes a first lever 345 pivotally connectedwith the scroll partition 332, a second lever 346 connected with thefirst lever 345, and a third lever 347 connected with the second lever346, wherein the scroll partition 332 moves according to operation ofthe third lever 347.

An elastic portion 350 is provided for supplying restoring force to thescroll partition 332.

The scroll partition 332 is disposed such that cross-sections of thefirst scroll 314 and the second scroll 316 decrease along an inflowdirection of the exhaust gas. In other words, the flowpaths along thefirst scroll and second scroll have decreasing cross-sections.

When the turbine 312 rotates, a compressor 360 connected with theturbine 312 rotates and takes in air.

Hereinafter, referring to FIG. 3 to FIG. 6, operation of the variableturbocharger according to the exemplary embodiments of the presentinvention will be explained.

FIG. 3( a) and FIG. 4( a) illustrate operations of the variableturbocharger according to the exemplary embodiments of the presentinvention at low speed.

At low speed, the flux control valve 320 of the variable turbocharger ismaintained in a closed state, and the scroll partition 332 is maintainedin a protruded state for separating the first scroll 314 and the secondscroll 316.

At low speed, flux of the exhaust gas is less, and the A/R ratio is lessbecause the exhaust gas inflow cross-section is small and the velocityof the exhaust gas is fast. Thus reaction of the turbine 312 is fast sothat turbo lag may be minimized.

The inflowing exhaust gas is prevented from leaking so that energy lossin minimized.

FIG. 3( b) and FIG. 4( b) illustrate operations of the variableturbocharger according to the exemplary embodiments of the presentinvention at high speed.

At high speed, the flux control valve 320 of the variable turbochargeris maintained in an opened state, and the scroll partition 332 thatseparates the first scroll 314 and the second scroll 316 at low speed isinserted into the guide unit 342.

At high speed, flux of the exhaust gas is larger, and the A/R ratio islarger because exhaust gas inflow cross-section is large so that outputof the turbine 312 is improved.

Also, at high speed, the turbine 312 is turned by the exhaust gas withminimized resistance because there is no obstacle in the scrolls.

FIG. 5 illustrates the scroll partition 332, the guide unit 342, asupporting plate 348 for supporting the scroll partition 332, and acover 349.

FIG. 6 shows a partition controlling unit of the variable turbochargeraccording to exemplary embodiments of the present invention.

The first lever 345 is pivotally connected or coupled with the scrollpartition 332, the second lever 346 is connected with the first lever345, and the third lever 347 is connected with the second lever 346,wherein the scroll partition 332 moves according to operation of thethird lever 347.

FIG. 7 shows a partition controlling unit of a variable turbochargeraccording to various embodiments of the present invention.

FIG. 7 illustrates a first lever 445 pivotally connected with the scrollpartition 441, a second lever 446 connected with the first lever 445,and a third lever 447 connected with the second lever 446. The scrollpartition 441 moves according to operation of the third lever 447.

FIG. 8 shows a partition controlling unit of a variable turbocharger,which is in a lowering state or lifted state according to variousembodiments of the present invention.

A variable turbocharger according to the exemplary embodiments of thepresent invention includes a rack 456 disposed under a scroll partition432 and a drive gear 457 engaged with the rack 456.

The variable turbocharger according to the exemplary embodiments of thepresent invention is executed by rotation of the drive gear 457.

The drive gear 457 is operated by an actuator 440, and the actuator 440may be a motor or so on.

FIG. 9 shows a partition controlling unit of a variable turbochargerwhich is in a lowering state or lifted state, according to variousexemplary embodiments of the present invention.

A variable turbocharger according to the exemplary embodiments of thepresent invention includes an inclined unit 540 disposed under thescroll partition 532, and a drive lever 560 that moves along theinclined unit 540 for the scroll partition 432 to move.

An elastic portion 550 is provided to supply restoring force to thescroll partition 532.

The variable turbocharger according to exemplary embodiments of thepresent invention is operated according to engine speed, and thestandards of low or high speed are variable according to requirements ofengine performance.

FIG. 10 is a block diagram of a control method for a variableturbocharger according to the various embodiments of the presentinvention, and FIG. 11 is a flow chart for explaining the control methodfor a variable turbocharger according to the above exemplary embodimentsof the present invention.

Referring to FIG. 10 and FIG. 11, a control method for a variableturbocharger according to exemplary embodiments of the present inventionwill be explained.

A control method for a variable turbocharger according to the aboveexemplary embodiments of the present invention includes detectingvehicle information S10, determining exhaust gas inflow mode accordingto the vehicle information S20, opening/closing the flux control valveS30, and opening/closing the scroll partition S40.

The detecting vehicle information S20 uses at least one of a vehiclespeed sensor 610, a throttle opening sensor 620, an accelerationdetection sensor 630, and an accelerator pedal sensor 640, and is atleast one of vehicle speed, throttle opening, acceleration, andaccelerator pedal angle.

That is, an ECU (engine control unit) 650 receives information from thesensors, determines exhaust gas inflow mode according to the vehicleinformation, and controls the variable turbocharger by a partitioncontrolling unit 660.

Standards for determining mode depend on the kind of engine and requiredperformance, and may be selected and executed by a person skilled in theart given the detailed description, so a detailed explanation will beomitted.

The exhaust gas inflow modes include a first mode in which exhaust gasflows through a first scroll and a second mode in which exhaust gasflows through the first scroll and a second scroll.

The opening/closing of the flux control valve S30 includes selectivelyopening or blocking exhaust gas flowing into the second scroll.

The opening/closing of the scroll partition S40 includes selectivelyseparating the first scroll and the second scroll.

The opening/closing of the flux control valve S30 and theopening/closing of the scroll partition S40 may be simultaneouslyexecuted.

The opening/closing of the scroll partition S40 is executed with apartition controlling unit for opening/closing the scroll partition. Thepartition controlling unit includes a first lever pivotally connectedwith the scroll partition, a second lever connected with the firstlever, and a third lever connected with the second lever, wherein thescroll partition is opened/closed by rotation of the third lever.

Referring to FIG. 7, in a control method for a variable turbochargeraccording to the present invention the partition controlling unitincludes a first lever pivotally connected with the scroll partition, asecond lever pivotally connected with the first lever, and a third leverpivotally connected with the second lever, wherein the scroll partitionis opened/closed by rotation of the third lever.

Referring to FIG. 8, in a control method for a variable turbochargeraccording to the present invention the opening/closing of the scrollpartition S40 is executed with a partition controlling unit foropening/closing the scroll partition. The partition controlling unitincludes a rack disposed under the scroll partition and a drive gearengaged with the rack, wherein the scroll partition is opened/closed byrotation of the drive gear.

Referring to FIG. 9, in a control method for a variable turbochargeraccording to the present invention the opening/closing of the scrollpartition S40 is executed with a partition controlling unit foropening/closing the scroll partition. The partition controlling unitincludes an inclined unit disposed under the scroll partition and adrive lever moving along the inclined unit, wherein the scroll partitionis opened/closed by movement of the drive lever.

In the control method for a variable turbocharger according to variousembodiments of the present invention, repeated description of componentsof the variable turbocharger that were described according to previousexemplary embodiments of the present invention are omitted.

For convenience in explanation and accurate definition in the appendedclaims, the terms “up” or “upper”, “down” or “lower”, “front” or “rear”,“inside”, and etc. are used to describe features of the exemplaryembodiments with reference to the positions of such features asdisplayed in the figures.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

1. A variable turbocharger comprising: a turbine housing; a first scrollfluidly communicating with a turbine; a second scroll formed along anoutside of the first scroll, wherein the first scroll and the secondscroll are disposed within the turbine housing for exhaust gas toexhaust through the turbine; a partitioning unit for selectivelyseparating the first scroll and the second scroll; and a flux controlvalve disposed at the exhaust gas inflow portion and selectively coupledto the partitioning unit for blocking the exhaust gas from flowing intothe second scroll; and wherein the partitioning unit comprises: a scrollpartition that selectively separates the turbine housing between thefirst scroll and the second scroll; and a partition controlling unit fordriving the scroll partition; wherein the partition controlling unitcomprises: a guide unit configured to guide the scroll partition; and acontrolling link connected with the scroll partition and configured tomove the scroll partition along the guide unit; wherein the controllinglink comprises: a first lever pivotally coupled to the scroll partition;a second lever connected with the first lever; and a third leverconnected with the second lever; and wherein the scroll partition isconfigured to move based on an operation of the third lever.
 2. Thevariable turbocharger of claim 1, wherein the partition controlling unitcomprises: an inclined unit disposed under the scroll partition; and adrive lever moving along the inclined unit thereby causing the scrollpartition to move.
 3. The variable turbocharger of claim 1, wherein thescroll partition includes an elastic portion for supplying restoringforce.
 4. The variable turbocharger of claim 1, wherein the scrollpartition is disposed such that cross-sections of the first scroll andthe second scroll decrease along an inflow direction of the exhaust gas.5. A passenger vehicle comprising the variable turbocharger of claim 1,wherein the partitioning unit includes: a scroll partition thatselectively separates the turbine housing with the first scroll and thesecond scroll; and a partition controlling unit for driving the scrollpartition.
 6. A variable turbocharger comprising: a turbine housing; afirst scroll fluidly communicating with a turbine; a second scrollformed along an outside of the first scroll, wherein the first scrolland the second scroll are disposed within the turbine housing forexhaust gas to exhaust through the turbine; a partitioning unit forselectively separating the first scroll and the second scroll; and aflux control valve disposed at the exhaust gas inflow portion andselectively coupled to the partitioning unit for blocking the exhaustgas from flowing into the second scroll; wherein the partitioning unitcomprises: a scroll partition that selectively separates the turbinehousing between the first scroll and the second scroll; and a partitioncontrolling unit for driving the scroll partition; and wherein thepartition controlling unit comprises: a rack connected to the scrollpartition; and a drive gear engaged with the rack, wherein the drivegear drives the rack.
 7. The variable turbocharger of claim 6, whereinthe partition controlling unit comprises: a guide unit configured toguide the scroll partition; and a controlling link connected with thescroll partition and configured to move the scroll partition along theguide unit.
 8. The variable turbocharger of claim 6, wherein thepartition controlling unit comprises: an inclined unit disposed underthe scroll partition; and a drive lever moving along the inclined unitthereby causing the scroll partition to move.
 9. The variableturbocharger of claim 6, wherein the scroll partition includes anelastic portion for supplying restoring force.
 10. The variableturbocharger of claim 6, wherein the scroll partition is disposed suchthat cross-sections of the first scroll and the second scroll decreasealong an inflow direction of the exhaust gas.
 11. A passenger vehiclecomprising the variable turbocharger of claim 6, wherein thepartitioning unit includes: a scroll partition that selectivelyseparates the turbine housing with the first scroll and the secondscroll; and a partition controlling unit for driving the scrollpartition.